The present invention relates to an auxiliary mechanism for a three-point seat belt apparatus, and more particularly, to an auxiliary mechanism that aids a passenger when fastening a webbing of the seat belt apparatus and adjusts a webbing support position on an upper side of a seat back.
In the prior art, a seat belt apparatus includes a belt-like webbing, a tongue plate, and a buckle. In a vehicle seat having a seat back, the webbing is drawn from the upper side of the seat back to restrain the passenger seated on the seat. The tongue plate is arranged on the webbing so as to be movable along a longitudinal direction of the webbing. The tongue plate is engaged with the buckle. This type of a seat belt apparatus becomes fixed at three points when the passenger engages the tongue plate with the buckle. The webbing restrains the passenger's upper body from the shoulders to a diagonally lower portion in addition to restraining the passenger's waist.
When fastening this type of seat belt apparatus, the passenger who is seated on the vehicle seat must twist his or her upper body to grasp the webbing. Therefore, the webbing is not easy to fasten. In particular, for a rear seat, the webbing is held in close contact with the front surface of a seat back. Thus, it is difficult to grasp the webbing and difficult to fasten the seat belt apparatus.
Accordingly, Japanese Laid-Open Patent Publication No. 2007-45189 discloses a seat belt fastening auxiliary apparatus including a grasping unit arranged at a distal end of a fastening auxiliary arm and used to grasp the webbing. In the auxiliary apparatus, the fastening auxiliary arm is pivoted when fastening the seat belt apparatus so as to move the grasping unit toward the front of the seat back. This moves the webbing together with the grasping unit toward the front of the seat back so that the passenger can easily grasp the webbing.
In the above-described publication, the webbing is drawn out of a through-anchor located on one side at an upper end of the seat back. The webbing is extended from the position of the through-anchor to the position of the buckle to restrain the upper body of the passenger. In this manner, the position of the through-anchor is fixed. Thus, the webbing, which should be drawn out from a desired position above the shoulder of the passenger, may be located at a position that is too high or too low. Since passengers have different physical frames, preferable fastening may not be possible for each passenger.